Bolt anchor with spring rotation preventing means



Dec. 8, 1953 R. K. sKlNNl-:R 2,661,649

BOLT ANCHOR WITH SPRING ROTATION PREVENTING MEANS Filed April 20, 1950MJ Y W f fw lm llllill /NVEN TOR A 7' TORNEI*l Patented Dec. 8, 1953UNITED STATES PATENT OFFICE BOLT ANCHOR WITH SPRING ROTATION PREVENTINGMEANS 2 Claims.

The invention relates to bolt anchors of the expansible type which aredesigned to be located in holes in walls, ceilings, oors and the likefor receiving the threaded ends of bolts that are to secure in placeobjects such as signs, conduits, machinery and the like.

I-Ioles drilled in brittle materials, such as brick and concrete, toreceive such anchors are unavoidably liable to be conical in shape nearthe mouth due to chipping. Certain commonly used anchors are designed togrip the inner surface of the hole immediately adjacent its mouth wherethe conical shape of the hole provides an inefficient gripping surface.With such prior constructions it frequently happens, especially if theanchor does not tightly lit the hole, that the anchor rotates with thebolt when the bolt is turned for expanding the anchor, the result be ingthat the shell or expansion members of the anchor are not caused to moveoutwardly to grip the surface of the hole. It also frequently happensthat the anchor does not rotate with the bolt as last above-mentioned,but that the entire anchor nevertheless moves longitudinally withoutexpansion by the expansion nut as the said nut is longitudinally movedby the bolt toward the mouth of the hole. The anchor is thus moved awayfrom its desired position until it reaches the mouth of the hole whereit is caused to expand due to pressure against the object to be held.

Some of the dihiculties incident to the comu monly used prior boltanchors are eliminated when such anchors incorporate the inventiondisclosed and claimed in my Patent No. 2,399,069 dated April 23, 1946.As disclosed in the patent, spring fingers or springs are provided onthe anchor, these ngers or springs projecting toward the mouth of thehole and engaging at their ends with the surface of the hole. The saidiingers or springs bite into the said surface to prevent rotativemovement of the anchor and also to prevent longitudinal movement thereoftoward the mouth of the hole.

The general object of the present invention is to provide a bolt anchorhaving some of the features yset forth in the said patent and alsohaving certain additional advantages.

A more specific object of the present invention is to provide a boltanchor of the character set forth in the patent wherein the springs areso formed and positioned that they engage the surface of the holebetween their ends, thus frictionally resisting longitudinal movementwithout positively preventing it.

l as shown in Fig. l.

Another more Ispecific object of the present invention is to provide abolt anchor of the character set forth in the patent wherein the springsare located between the ends of the anchor, thus making it possible forthe anchor to have any desired longitudinal position irrespective of thesprings. The springs when engaged with the surface of the hole Aserve tobias thel Fig. 1 is a side view of an unexpanded bolt anchor embodyingthe invention together with an associated bolt, the anchor and boltbeing shown in a hole in a wall with a member in position to be held bythe bolt.

Fig. 2 is a fragmentary top view of portions of the anchor and bolt.

Fig. 3 is a fragmentary view similar to Fig. 1, but with the bolt anchorexpanded.

Fig. 4 is a vertical longitudinal sectional view of the anchor as shownin Fig. 1.

Fig. 5 is a left end view of the anchor and bolt Fig. 6 is a transversesectional View taken along the line 8 6 of Fig. 4.

Fig. '7 is a transverse sectional view taken along the line 'l-l of Fig.4.

Fig; 3 is a side View of an unexpanded bolt anchor constituting analternative embodiment of the invention. v

Fig. 9 is a. longitudinal vertical sectional view of the anchor as shownin Fig. 8.

Fig. 10 is a plan view of the anchor as shown in Fig. 9. y

Referring to Fig. l of the drawing, i9 repre sents a concrete wallhaving a hole l2 therein.

A bolt iii extends into the hole l2 and serves to The anchor as shown inFigs. 1 to 7 includes radially expansible gripping means. Morespecifically, the gripping means comprise two similar but somewhatdirerent radially movable eXpansion or gripping members i8 and 20. Thetwo members cooperate to substantially surround the bolt I4 and they areadapted to be located within the annular space between the bolt and thesurface of the hole I2. When the members I8 and 20 are in theirinnerpositions, their adjacent edges are in contact or substantially incontact as shown in Fig. 6. The said members are preferably providedrespectively with longitudinal slots 22 and 2 which are open at theirleft ends and closed at their right ends. The slot 22 provides themember I8 with two tongues 26 and 28 and the slot 24 provides the member20 with two tongues 30 and 32. The tongues 26, 28, 30 and 32 of themembers I8 and 20 are provided with longitudinally spacedcircumferentially extending teeth 34, 34 which are adapted to engage thesurface of the hole I2 when the said members are moved outwardly ashereinafter explained.

The members IB and 26 are semicylindrical at their right ends. Onemember which may be the member I8 is provided with an arcuate groove 36and the other member which may be the member 20 is provided with ashorter arcuate groove 38. The member 26 is provided with integral tabs40 and 42 which enter the groove 36 and which are curved inwardly so asto serve to loosely retain the two members in engaged reiationship.

A suitable wedging means is provided, and as shown the said wedgingmeans is a nut 4i!- which is internally threaded to receive and fit thethreaded portion of the bolt I4. The nut 44 is initially at theA left asshown in Figs. 1 and 4. The nut 44 is square in transverse section andit is tapered with its outer faces converging toward the right. Thetongues 26, 28, 30 and 32 have inclined flat inner faces which areengaged respectively with the inclined outer faces of the nut.

Preferably one of the tongue which may be the tongue 28 is provided atits left end with an inwardly extending tab 46 which is engageable withthe end face of the nut 44, as clearly shown in Fig. 2. rIhe tab 46serves to limit relative movement of the gripping members i8 and 2Etoward the right. The tab 46 is of such size that it does not engage thebolt I4 which can extend through and beyond the nut to any desiredextent, as shown in Figs. 1 and 2.

In accordance with the present invention, a plurality of separate bowedspring members is provided, the said spring members being connected withthe anchor and extending longitudinally and being relatively narrow. Asshown, there are two oppos-itely disposed spring members 48 and 50 hichare respectively carried by and directly connected with the tongues 26and 32 of the gripping members. The members 48 and 50 are formed ofspring steel and are relatively stiff. The said spring members haveoutwardly bowed portions intermediate their ends, the said bowedportions preferably being also intermediate the ends of the grippingmembers. The said bowed portions are positioned for engagement with thesurface of the hole within which the anchor is located.

As more clearly shown in Fig. 4, the tongues 26 and 32 are formedrespectively with centrally disposed longitudinal external grooves 52and 54 and with centrally disposed longitudinal internal grooves 56 and58. The groove 52 extends toward the left from the arcuate groove 36 andthe groove 54 extends toward the left from the arcuate groove 38. Thegrooves 56 and 58 are at the left with their right ends respectivelyadjacent the left ends of the grooves 52 and 54. Radial holes connectthe left ends of the grooves 52 and 54 with the right ends of thegroove-s 56 and 58. Each of the spring members Y48 l,and 5c has anoutwardly bowed portion the ends of which are in the correspondingouter'groove 52 or 5d. Each of the said members has an offset portionwhich extends through the corresponding radial hole and each of the saidmembers has a short straight portion which is within the correspondinginner groove 56 or 56. Each spring member can be assembled with itstongue by inserting its short straight portion through the correspondingradial hole and then swinging the member inwardly to the position shown.When the nut 44 is in place it engages the short straight portions ofthe spring members to hold the said members in the positions shown.

When the parts of the anchor are assembled with the nut 44 in itsinitial relative position at the left as shown in Fig. 1 and with thesaid nut engaged with the bolt I4, the bolt and the anchor can beinserted in a hole such as the hole I2. The tab 46 by reason of itsengagement with the nut 44 insures movement of the entire anchor withVthe bolt. The diameter of the yhole I2 is such that the bowed portionsof the spring members 48 .and 56 engage the surface of the said hole,the said bowed .portions being partly attened, as shown.

The said bowed portions of the spring membersv serve as krunners toguide longitudinal movements of the anchor and to centralize the anchorwithin the hole. The said bowed portions are in rm engagement with theAsurface of the hole and therefore resist longitudinal and rotativemove.- ments. The vanchor is shown as substantiallyr spaced from theentrance end of the hole I2 as is preferable, but it will be understoodthat if desired the anchor may be located with its rightv end flush withthe face of the wall I0.

With the anchor and bolt located as shown in Fig. 1, the bolt I4 isturned to relatively move the nut ,44 toward the right from its saidinitial position as shown in Fig. 1 to its gripping position as` shownin Fig. 3. The bowed portions of thespring members act frictionally toresist any tendency of the main expansion or gripping members to movetoward the right with the nut. The bowed portions of the spring membersalso serve to prevent any rotation of the entire anchor with the -boltas the bolt is turned. The edge corners of the spring member arerelatively sharp and they bite into the rough surface of the interior ofthe hole I2 to positively prevent rotative movement. As the nut 44 ismoved toward the right and toward its gripping position, the leftportions of the expansion or gripping members are forced outwardly, thetwo tongues of each member being slightly deflected relatively to eachother as they move outwardly. The teeth 34 on the tongues are forcedinto locking or gripping engagement with the interior of the hole andthe anchor is securely held in place. The head of the bolt engages themember I6 to be held, and the turning of the bolt is continued until themember I6 is securely locked in place. As the expansion or grippingmembers move outwardly, the bowed portions of the spring members areadditionallyflattened, this being permitted by the longitudinal grooves52 andr 54. When the gripping members reach their outer positions, thebowed portions of the spring members are substantially entirely withinthe grooves 52 and 54.

The bowed portions of the spring member resist longitudinal movement aspreviously stated, but they do not positively prevent it. It istherefore possible to readily release the member i6 when desired. Thebolt I4 is reversely turned to relatively move the nut 44 from itsgripping position to its initial position as shown in Fig. 1. As the nutmoves to the said initial position, the spring members press or bias theexpansion or gripping members inwardly to the extent permitted by thenut, the said expansion or gripping members being thus moved out ofengagement with the surface of the hole i2 and to the positions shown inFig. 1. Then the bolt and the anchor can be withdrawn by applyingsuiiicient force to overcome the frictional resistance resulting fromthe engagement of the bowed portions of the spring members with thesurface of the hole.

Figs. 8 to l0 illustrate an alternative embodiment of the invention.These views show only the alternative anchor and do not show the bolt.

Two similar radially movable gripping members 60 and 62 are provided,these being generally semi-cylindrical and having a central opening forthe bolt. Preferably, the said members are annularly grooved at theirperipheries and are resiliently held in the proper relationship byspring bands 64 and 66 located in the grooves.

Located adjacent the ends of the expansion or gripping members 6I] and62 are two wedge members 68 and 10. The member 68 constitutes anexpansion nut and it is internally threaded to engage the threadedportion of the bolt. The member or nut 68 has an initial position at theleft as shown. Except for the threads, the members 68 and 'I0 aregenerally similar. Each of the members 68 and ll has an inner taperedportion 'I2 with inclined external faces which engage similarly inclinedinternal faces on the members 60 and 62. Each of the said members 68 and'I0 also has an outer tapered portion 74 with inclined external faceswhich engage inwardly projecting ribs 16, 16 on the members 6i) and 62.There is an oiset between the portions 12 and 'i4 of each member and thecorresponding ribs 16, 76 of the expansion members engage the offset tolimit longitudinal movement of the wedge member. Preferably, each of themembers 68 and 70 is also provided with oppositely disposed taperedprojections 16 which are located between the members 60 and 62, the lastsaid members being bevelled to receive the said projections.

A plurality of separate bowed spring members is provided, the saidspring members being connected with the anchor. Preferably, there aretwo spring members 'I8 and 30 which are identical in shape with thespring members 4B and 50.

The expansion or gripping members 6i) and B2 are provided withlongitudinal external grooves 82 and 84 similar to the grooves 52 and 54and with longitudinal internal grooves 86 and 88 similar to the grooves56 and 58, and they are also provided with radial holes connecting thesaid grooves. The spring members 'i8 and 80 are entered in the grooves82, 84, 8B and 88 in the manner previously described in connection withthe spring members 48 and 50.

When the anchor, as shown in Figs. 8 to 10, is engaged with a bolt suchas the bolt I4, the anchor and the bolt can be inserted in a hole suchlas the hole l2. The spring members 18 and 6 80 serve as previouslydescribed to guide and centralize the anchor within the hole and toresist longitudinal movement. When the bolt is turned, the threadedmember or nut 68 is forced toward the right from its initial position toa gripping position. In moving toward the right the member or nut 68 isforced toward the opposite member 'l0 and the two expansion or grippingmembers 60 and 62 are forced apart and into locking or grippingengagement with the surface of the hole. When the members 60 and 62reach their outermost locking or gripping positions, the bowed portionsof the spring members are entirely flattened and lie within the grooves18 and 80. The spring members 'I8 and 80 not only resist longitudinalmovement, but by reason of their sharp corners prevent rotative movementof the expansion members.

As previously described in connection with the anchor shown in Figs. 1to 7, the anchor shown in Figs. 8 to 10 can be released by reverselyturning the bolt, the bowed portions of the spring members serving topress the expansion members inwardly. The bolt and the anchor can beremoved byovercoming the frictional resistance oiered by the springmembers.

The invention claimed is:

1. A bolt anchor comprising in combination, a plurality of radiallyoutwardly movable gripping members provided with longitudinal grooves inthe outer faces thereof and having initial inner positions, a wedgingnut located at least partly between the gripping members, means on saidgripping members to normally maintain said nut at least partiallybetween said gripping members, said nut being engageable with a bolt sothat upon rotation of the bolt the nut is longitudinally movedrelatively to the gripping members for moving the said members outwardlyfrom their said inner positions into engagement with the surface of ahole in which the anchor is located, and a plurality of longitudinallyextending narrow spring members separate from the gripping members,lmeans for securing one end of each of said spring members to itsrespective gripping member to prevent relative longitudinal movementtherebetween, each of said spring members having its end portionsengaging the gripping members and intermediate portions that areinitially bowed outwardly but are in register with the said grooves, thesaid bowed portions of the spring members having pressure engagementwith the said surface of the said hole when the gripping members are intheir said inner positions so as to guide the entire anchor forlongitudinal movement in either direction upon correspondinglongitudinal movement of the bolt and so as to provide frictionalresistance to longitudinal and rotative movements of the grippingmembers when the bolt is rotated to longitudinally move the nut and thesaid end portions of the springs being outwardly movable relatively tothe bowed portions as the gripping members are moved outwardly by thenut so as to increase the pressure of the bowed portions against thesurface of the hole with a resultant increase in the said frictionalresistance provided by the said bowed portions.

2. A bolt anchor as set forth in claim 1, wherein said means forsecuring said spring members includes a radial hole in each grippingmember adjacent the nut which communicates with the said groove in theouter face and wherein each gripping member also has a longitudinalgroove in its inner face adjacent the nut which com- 7 munioates withthe said hole, :and wherein each spring member has a portion extendingthrough the `corresponding radial hole and rfils() has a portion Withinthe groove in the inner face of the corresponding gripping member, thelast said portion of each spring member being engaged by the nut to holdthe said spring member in place.

ROBERTS K. SKINNER.

References Cited in the file 'of this patent UNITED STATES PATENTSNumber Name Date Schenker Mar. 2l, 1882 Boone v Feb. 3, 1903 DefenbaughAug, 30, 19710 Rosen Feb. 1931 McArthur Apr. 26, 1932 Skinner Apr. 2'3,1946 Kempton Sept. 5, 1950.

